Galvanometer



Aug. 14, 192s. 1,680,420

J. w. LEGG GALvANouEm Original Filed Sept. 8. 1920 2 Sheets-Sheet lFf'g. 'j 8 /FIJ /2 '1. a i i IZ' l i l` l l l: l I: Aa LJ J L 7/5 /6 1.76//6 /5 e 2 3 u 4E //l "Q /4 /5 C3 w Ess 1 mvENToR Q f f V Jaap/lime.

BY wav 61M. ATTORNEY Patented Aug. 14, 1928.

UNITED STATES PATENT OFFICE.

JOSEPH W. LEGG, 0F WILKINSBURG, PENNSYLVANIA, ASSIGNOB TO WESTINGHOUSEELECTRIC & MANUFACTURING COMPANY, A CORPORATION 0F PENNSYLVANIA.

GALVANOMETER.

Original application filed September 8, 1920, Serial No. 408,954.Divided and this application led May 25,

1925. Serial No. 32,546.

My invention relates to electrical measuring instruments andparticularly to galvanometers.

`One object of my invention is to provide a galvanomcter that shallcontrol a plurality of indicating devices by a single magnetic circuit.

Another object of my invention is to provide a galvanometerr that is ofunitary construction and capable of being embodied within otherelectrical apparatus.

Another object of my invention is to provide a galvanometer with asingle magnetic circuit having a plurality of air-gaps therein that areso insulated that conductors having varying potentials impressed thereonmay be safely inserted in the air gaps.

4It is also an object of my invention to provide a galvanometer thatshall be particu larly adapted for insertion into electrical instrumentssuch as oscillographs and the like.

A further object of my invention is to provide a galvanometer that shallbe adapted for operation from a plurality of circuits by a singleelectromagnet.

IThe subject-matter of the present application is a division of myapplication, Serial No. 408,954, filed September 8, 1920, relating tooscillographs.

In the accompanying drawings,

Figure 1 is a plan view of a galvanometer embodying my invention,

Fig. 2 is a side view, partially in elevation and partially in section,taken along thek section line II--II of Fig. 1,

Fig. 3 is a front elevational view of the vibrating element of thegalvanometer, and

Fig. 4 is a side view, partially in section and partially in elevation,of the vibrating element shown in Fig. 3.

My invention comprises, in general, an electromagnet l having polepieces 2 and 3 between which are disposed auxiliary pairs of pole pieces4, 5 and 6 for controlling vibrating elements 7, to be hereinafter morefully described.

The electromagnet 1 comprises a winding 8.that may be energized from anysuitable source of electromagnetic force connected to terminals 9. Thewinding 8 should preferably be energized by direct current of constantvalue. A cylindrical core member l1 is secured within the winding 8 bynuts 12 that also secure thereto the pole pieces 2 Renewed January 6,1928.

and The pole pieces 2 and 3 extend a. substantial distance at rightangles 4to the core member 1l.

The three pairs of pole pieces 4, 5 and 6 are disposed in seriesrelation between the pole pieces 2 and 3.` The pole pieces of each pairare separated by relatively small air gaps 13, the cross-sectional areaof pairs of the pole pieces at the air gaps 13 being relatively small toconcentrate the magnetic iuX thereat. The cross-sectional area. of thebases 14 of the several pole pieces is relatively large, and insulatingmembers 15 are placed between the adjacent bases and between each ot'the pole pieces 2 and 3 and the adjacent pole piece of the series. Thisarrangement is provided in order that the various elements shall beinsulated from each other and in order to decrease the reluctance of thecircuit.

Casings 16 surround each of the pairs of pole pieces and are adapted toreceive the vibrating elements 7. Referring particularly to Figs. 3 and4, each of the vibrating elements 7 comprises a main body portion 17,upon which are mounted terminal members 18 and bridging members 19 overwhich is disposed a filament 21 that surrounds a pulley 22, and whichhas a small mirror 23 disposed thereon. The pulley 22 is of insulatingmaterial and is mounted at one end of a pivoted member 24, the other endof which is operatively connected to an adjustlng spring 25.

With this arrangement, the member 24 is so balanced as to its inertiathat any jars are absorbed and the likelihood of breakage of thefilament is greatly reduced. When the vibrating elements 7 are placed inthe receptacles 16, the filaments 21 are disposed in the magnetic fieldsof the air gaps 13 and thus the mirrors 23 will be turned an amountproportional to the current traversing the filament and, if a beam oflight is directed to the mirror, this beam of light will be instantlydeiected an amount proportional to the instantaneous value of thequantity being measured. Since the energization of the winding 8 of theelectromagnet 1 is constant, the flux traversing the several air gapswill be constant, whereby the variable quantity measured is the currenttraversing each of the laments 21 from the respective terminals 18, thelatter being connected to any desirable external circuit.

The mirrors 23 may be located so that the rays therefrom may play uponany desired reflecting surface, film, or the like according to theapparatus with which the galvanometer cooperates.

My invention is not limited to the specific details illustrated as itmay be variously modified without departing from the spirit and scope ofthe invention, as set forth in the appended claims.

I claim as my invention:

1. A galvanometer for an oscillograph comprising an energizing coil, acore member therefor, three pairs of pole members disposed in seriesbetween the poles of the core member, and insulating means forseparating said pairs of pole -members from each other.

2. A galvanometer for an oscillograph comprising a magnetizable coremember, a plurality of pairs of pole pieces disposed between the polesof the core member and havmg an air gap between the poles of each pair,and insulating means between the said pairs of pole pieces.

3. A galvanometer for an oscillograph comprising a magnetizable coremember, a plurality of pairs of pole pieces disposed between the polesof the core member and having an air gap of relatively smallcrosssectional area between the poles of each pair and of largecross-sectional area between the said pairs of pole pieces, and meansfor effectively insulating the pairs of pole pieces from each other.

ll. A galvanometer for an oscillograph comprislng an energizing coil, acore member therefor, a plurality of pairs of pole pieces disposedbetween the poles of the core member and having an air gap of relativelysmall cross-sectional area between the poles of each pair, said polepieces having air gaps of relatively large cross-sectional areas betweenthe several pairs and between the poles of the core member and the outerends of the end pairs.

5. The combination with a magnetizable structure constituting acontinuous unin terrupted flux path and energizing means therefor, of aplurality of pairs of pole members disposed in series in said iiux pathand insulated from each other.

6. The combination with a magnetizable oke structure constituting acontinuous uninterrupted flux path, of a plurality of pairs of polemembers disposed in series between the legs of the yoke and insulatedfrom each other.

7. A galvanometer comprising two magnetizable members disposed in theflux path of the galvanometer and having adjacent surfaces extendingtransversely to said path, and a body of insulating materialsurrounding, and disposed between said members adjacent to saidsurfaces.

8. An instrument comprising a magnetizable core member, a pair of polemembers disposed in series magnetic-fiuX-path relation thereto, meansdisposed in the air gap of said pole members for (3o-operation with thefiux field therebetween and a body of insulating material constituting apartition between one of said pole members and said core member.

In testimony whereof, I have hereunto subscribed my name this 14th dayof May 1925.

JOSEPH W. LEGG.

